[Bug] 2.0.2版本 设置设备模板后，插入数据报错

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar.

### Version

2.0.2

### Describe the bug and provide the minimal reproduce step

1.创建设备模板
2.挂载设备模板
3.使用maven项目引入依赖

org.apache.iotdb
iotdb-session
2.0.2

4.使用以下方法插入设备数据
sessionPool.insertRecord(deviceId, time, measurements, tsTypes, values);

### What did you expect to see?

数据成功插入到数据库

### What did you see instead?

iotdb数据库报错日志

2025-04-29 11:17:54,999 [pool-56-IoTDB-ClientRPC-Processor-1$20250429_031754_00048_1.1.0] WARN o.a.i.d.q.p.s.FragmentInstanceDispatcherImpl:514 - write locally failed. TSStatus: TSStatus(code:305, message:internal error. statemachine throws a runtime exception: java.lang.NullPointerException), message: internal error. statemachine throws a runtime exception: java.lang.NullPointerException
2025-04-29 11:18:55,506 [1@group-000200000009-StateMachineUpdater] ERROR o.a.i.c.r.ApplicationStateMachineProxy:157 - application statemachine throws a runtime exception:
java.lang.NullPointerException: null
at org.apache.iotdb.db.schemaengine.rescon.MemSchemaEngineStatistics.lambda$getTemplateSeriesNumber$0(MemSchemaEngineStatistics.java:142)
at java.util.stream.ReferencePipeline$5$1.accept(ReferencePipeline.java:227)
at java.util.concurrent.ConcurrentHashMap$EntrySpliterator.forEachRemaining(ConcurrentHashMap.java:3606)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.LongPipeline.reduce(LongPipeline.java:438)
at java.util.stream.LongPipeline.sum(LongPipeline.java:396)
at org.apache.iotdb.db.schemaengine.rescon.MemSchemaEngineStatistics.getTemplateSeriesNumber(MemSchemaEngineStatistics.java:144)
at org.apache.iotdb.db.schemaengine.rescon.MemSchemaEngineStatistics.getTotalSeriesNumber(MemSchemaEngineStatistics.java:124)
at org.apache.iotdb.db.schemaengine.rescon.MemSchemaRegionStatistics.getGlobalSeriesNumber(MemSchemaRegionStatistics.java:230)
at org.apache.iotdb.db.schemaengine.schemaregion.impl.SchemaRegionMemoryImpl.activateSchemaTemplate(SchemaRegionMemoryImpl.java:1358)
at org.apache.iotdb.db.consensus.statemachine.schemaregion.SchemaExecutionVisitor.visitActivateTemplate(SchemaExecutionVisitor.java:436)
at org.apache.iotdb.db.consensus.statemachine.schemaregion.SchemaExecutionVisitor.visitActivateTemplate(SchemaExecutionVisitor.java:94)
at org.apache.iotdb.db.queryengine.plan.planner.plan.node.metadata.write.ActivateTemplateNode.accept(ActivateTemplateNode.java:175)
at org.apache.iotdb.db.consensus.statemachine.schemaregion.SchemaRegionStateMachine.write(SchemaRegionStateMachine.java:182)
at org.apache.iotdb.consensus.ratis.ApplicationStateMachineProxy.applyTransaction(ApplicationStateMachineProxy.java:153)
at org.apache.ratis.server.impl.RaftServerImpl.applyLogToStateMachine(RaftServerImpl.java:1839)
at org.apache.ratis.server.impl.StateMachineUpdater.applyLog(StateMachineUpdater.java:255)
at org.apache.ratis.server.impl.StateMachineUpdater.run(StateMachineUpdater.java:193)
at java.lang.Thread.run(Thread.java:748)

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Bắt đầu với db/schemaengine/rescon/MemSchemaEngineStatistics.java tại getTemplateSeriesNumber, đặc biệt là dòng 142, sau đó lần theo đường dẫn kích hoạt thông qua SchemaRegionMemoryImpl.activateSchemaTemplate. Tái hiện việc thiết lập device-template và lệnh gọi sessionPool.insertRecord trên phiên bản 2.0.2; hoàn tất khi việc kích hoạt template không còn phát sinh NullPointerException và thao tác chèn dữ liệu thành công.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.